Submitted to: Journal of Food Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/21/2010
Publication Date: 10/1/2010
Publication URL: http://hdl.handle.net/10113/44426
Citation: Kumar, P., Sandeep, K.P., Alawi, S., Truong, V., Gorga, R.E. 2010. Preparation and characterization of bio-nanocomposite films based on soy protein isolate and montmorillonite using melt extrusion. Journal of Food Engineering. 100(3):480-489. Interpretive Summary: The non-degradable and non-renewable nature of plastic packaging has led to a renewed interest in packaging materials based on biopolymers such as proteins, starch, cellulose and other polysaccharides derived from renewable sources. This study aimed to develop a technique to prepare bio-nanocomposite films based on soy protein isolates (SPI) and modified montmorillonite (MMT) using melt extrusion. Effects of pH of film forming solution, MMT content, and extrusion processing parameters (screw speed and barrel temperature distribution) on the structure and properties (mechanical, dynamic mechanical, thermal stability, and water vapor permeability) of SPI-MMT bio-nanocomposite films were investigated. The results show the feasibility of using bio-nanocomposite technology to improve the properties of SPI-based biodegradable films. This technology can also be applied to biopolymers based on starch and other proteins. These bio-nanocomposite films could potentially be used in food packaging to replace some of the existing plastics such as low density polyethylene (LDPE) and polyvinylidene chloride (PVDC). However, there is a need to further improve the properties of these SPI-MMT films for commercial application.
Technical Abstract: The non-biodegradable and non-renewable nature of plastic packaging has led to a renewed interest in packaging materials based on bio-nanocomposites (biopolymer matrix reinforced with nanoparticles such as layered silicates). Bio-nanocomposite films based on soy protein isolate (SPI) and montmorillonite (MMT) were prepared using melt extrusion. Effects of pH of film forming solution, MMT content, and extrusion processing parameters (screw speed and barrel temperature distribution) on the structure and properties of SPI-MMT bio-nanocomposite films were investigated. X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) were used for structural characterization of the films. Properties of the films were determined by tensile testing, dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), and water vapor barrier measurement. The arrangement of MMT in the soy protein matrix ranged from exfoliated at lower MMT content (5%) to intercalated at higher MMT content (15%). There was a significant improvement in mechanical (tensile strength and percent elongation at break) and dynamic mechanical properties (glass transition temperature and storage modulus), thermal stability, and water vapor permeability of the films with the addition of MMT. The results presented in this study show the feasibility of using bio-nanocomposite technology to improve the properties of biopolymer films based on SPI.